Flexible film for making microrobots, smart springs

Scientists invent a flexible bilayer film that shrinks and expands in response to light.

Biplab Das

A research team has created a flexible bilayer film that can rapidly bend, stretch and curl in response to visible light.

The film, made of single-walled carbon nanotube and a polymer, is potentially useful for making tiny motors that will find applications in light-activated sensors, artificial muscles and energy generators.

The scientists, led by Gilles Lubineau from King Abdullah University of Science and Technology (KAUST), Saudi Arabia, and Fudan University, China, have found that light-induced variations in thermal expansions and changes in water content of the film materials caused the polymer layer of the film to expand and the carbon nanotube layer to shrink.

Exploiting the properties of the film, the researchers also made a microrobot whose front part scrabbled as the back part pedalled the air to move forward.

In addition, each end of the film could act like an artificial hand that stretches in light and curls smoothly in darkness, showing ability to grasp and lift a polystyrene sponge three times its weight, they say.

“The bilayer film exhibits reversible shape changes in response to light and could potentially respond to other environmental stimuli such as pH, moisture, thermal, electrical and chemical energy,” says Yanlong Tai, lead author of the study.